# Tag history strange behaviour

**URL:** <https://forum.inductiveautomation.com/t/tag-history-strange-behaviour/24963>\
**Category:** Ignition\
**Created:** [May 14, 2019, 11:24am UTC](https://forum.inductiveautomation.com/t/tag-history-strange-behaviour/24963 "2019-05-14T11:24:59Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![chris.roys](https://avatars.discourse-cdn.com/v4/letter/c/e9c0ed/32.png) [@chris.roys](https://forum.inductiveautomation.com/u/chris.roys)\
**Post date:** [May 14, 2019, 11:24am UTC](https://forum.inductiveautomation.com/t/tag-history-strange-behaviour/24963/1 "2019-05-14T11:24:59Z")

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I setup tag history for some Boolean tag with following setting:  
Scanclass: Evalute on change  
His. Deadband: 0.01  
Value mode: Discrete  
Max Time …: Unlimited  
I also setup table report with sample Size: Onchange. So it should only show me the new row if one of my tag value change compare to previous one.  
But in action query return many row with same value for all tags. For clarity I attach my setting snapshot. Why there is so many log when there is no vlaue change in tags value?

 ![Untitled](https://us1.discourse-cdn.com/inductiveautomation/original/2X/d/d2b6ca67770bb0f4224d2c8d1c3fb99da2973fbc.png)

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**Author:** ![bpreston](https://avatars.discourse-cdn.com/v4/letter/b/4af34b/32.png) [@bpreston](https://forum.inductiveautomation.com/u/bpreston)\
**Post date:** [May 14, 2019, 6:04pm UTC](https://forum.inductiveautomation.com/t/tag-history-strange-behaviour/24963/2 "2019-05-14T18:04:19Z")

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Try looking at your quality. Even though you marked Ignore Bad Quality, my experience has been every time the tag goes bad then comes back you will get a new entry showing it is good quality. This can cause the extra entries you are seeing. You may have to do a script to filter out values that haven’t changed.

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**Author:** ![chris.roys](https://avatars.discourse-cdn.com/v4/letter/c/e9c0ed/32.png) [@chris.roys](https://forum.inductiveautomation.com/u/chris.roys)\
**Post date:** [May 15, 2019, 11:39am UTC](https://forum.inductiveautomation.com/t/tag-history-strange-behaviour/24963/3 "2019-05-15T11:39:25Z")

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My tags are all Memory so their quality is always good.  
I think I found the problem here. yesterday I change the Historical deadband from 0.01 to 1 for Boolean tag, it seems every thing log correctly. It seems there is bug for Historical deadband.

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**Author:** ![vipo](https://avatars.discourse-cdn.com/v4/letter/v/eada6e/32.png) [@vipo](https://forum.inductiveautomation.com/u/vipo)\
**Post date:** [June 23, 2020, 8:08pm UTC](https://forum.inductiveautomation.com/t/tag-history-strange-behaviour/24963/4 "2020-06-23T20:08:13Z")

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I have this same problem.  
It is the same for every boolean tag.